The mechanism of synergistic hormone interaction is being studied in silkmoth wing epidermal cells using the developmental model of pupa-to-adult versus pupa-to-second-pupa. Protein, RNA and DNA synthesis are all being determined within hours of hormone stimulation as well as during the first six days of development. Specific protein synthesis will be studied using 2 dimensional slab gel electrophoresis combined with autoradiography. In conjunction with specific protein synthesis, the binding of 3H-ecdysone and 3H-juvenile hormone to nuclear components will be determined in order to correlate nuclear events with a biological response. The effect of juvenile hormone on the stimulation of RNA polymerase II by ecdysterone will also be studied in vivo to complement our previously reported in vitro studies. The changes in the various RNA polymerase will be measured by separation and characterization using column chromatography. These studies will aid in our understanding of the mechanism of action of steroid and terpenoid hormones and the regulation of cellular growth and differentiation.